Heretofore, in arrangements employing hydraulic pumps and hydraulic motors for driving hoist drums, various systems and devices were proposed for preventing the accidental release of the load being lifted. However, such prior art systems have been generally complicated and costly to construct and, in many instances, especially where the system which was intended to prevent total accidental loss or release of the load actually comprised a portion of the power transmission or power train, such prior art systems were prone to failure.
Accordingly, the invention as herein disclosed and described is primarily directed to the solution of the above as well as other attendant problems.